And for IEMs, how does the IEM card compare to Minibox and balanced? Because the lattter are more powerful, so do they not have more authority in the bass, or better dynamic. I really did not like how I felt the AK120 lacked power to properly drive even iems.

I can't say I have ever felt that the IEM card didn't drive the IEMs with authority or with sufficient bass. No complaints in that regard for me.

I’ve been very happy with my hm-901 since i got it in early november. Listening with my fitear mh335dw with the iem card to dsd sacd rips. Sounds really good. In fact i’ve been tthinking of using the hm-901 as a source with my balanced speaker rig.
Does anyone know if you can get a balanced line out signal from the hm-901?

I’ve been very happy with my hm-901 since i got it in early november. Listening with my fitear mh335dw with the iem card to dsd sacd rips. Sounds really good. In fact i’ve been tthinking of using the hm-901 as a source with my balanced speaker rig.
Does anyone know if you can get a balanced line out signal from the hm-901?

There isn't an adapter to run a balanced line out unfortunately. However, the 901 dock that is releasing soon might have the capability, but I'm not keeping my hopes up.

I have just got my new Hifiman HM 901 with balanced card, JH13ProFreq., AudioMoon Silver Dragon balanced cable with TRRS connector, Sandisk 128GB extreme card.
I loaded it with dff files and started to listen. I tried stock JH cable with balanced switch off, then I replaced cable for MoonAudio and switched the balanced on. I was glad I upgraded the cable, the difference was noticeable.

Overall, I'm very impressed with the player, iems and cable. Nevertheless, as for the HM 901, there are few questions I cannot find answer for.

1) car charger
The player cannot be charged via USB cable. So I ordered the "black frame" battery charger + replacement battery and thought that it would support USB charging. But there is no indication/diod on the frame, so I cannot check if it works.
Q: it there any information about the battery charger? Is there any other car charging solution?

2) firmware
Although I could read in the Settings of the HM901 that the firmware is 1.82 and kernel 2.9, I had some issues with the cue support ON (repeat. restarting) , so I got a suspicion that it may have not final but 1.82 beta version installed.
Q: is the "beta" info included in the settings (pe. "1.82 beta" or so?

3) firmware update
In connection with 2) I tried to update the HM901 with the 1.82 final "update.zip". I followed the instructions from Hifiman web, but it seemed that the player went to the recovery mode, but "froze" without any progress that should be automatic. I waited about 20min and then gave up and reset.
Q: how to update firmware? Did I something wrong? It was on Sandisk 128G extreme, my Mac shows exFAT stock partition.

4) volume adjustment
It may sound as a stupid question, but when I change volume, there is a short "crack" or "hissing" after switching to the next volume position, the higher the volume, the louder the crack. Then it plays normally.
Q: is there a similar experience, I mean is it normal?

I have just got my new Hifiman HM 901 with balanced card, JH13ProFreq., AudioMoon Silver Dragon balanced cable with TRRS connector, Sandisk 128GB extreme card.
I loaded it with dff files and started to listen. I tried stock JH cable with balanced switch off, then I replaced cable for MoonAudio and switched the balanced on. I was glad I upgraded the cable, the difference was noticeable.

Overall, I'm very impressed with the player, iems and cable. Nevertheless, as for the HM 901, there are few questions I cannot find answer for.

1) car charger
The player cannot be charged via USB cable. So I ordered the "black frame" battery charger + replacement battery and thought that it would support USB charging. But there is no indication/diod on the frame, so I cannot check if it works.
Q: it there any information about the battery charger? Is there any other car charging solution?

2) firmware
Although I could read in the Settings of the HM901 that the firmware is 1.82 and kernel 2.9, I had some issues with the cue support ON (repeat. restarting) , so I got a suspicion that it may have not final but 1.82 beta version installed.
Q: is the "beta" info included in the settings (pe. "1.82 beta" or so?

3) firmware update
In connection with 2) I tried to update the HM901 with the 1.82 final "update.zip". I followed the instructions from Hifiman web, but it seemed that the player went to the recovery mode, but "froze" without any progress that should be automatic. I waited about 20min and then gave up and reset.
Q: how to update firmware? Did I something wrong? It was on Sandisk 128G extreme, my Mac shows exFAT stock partition.

4) volume adjustment
It may sound as a stupid question, but when I change volume, there is a short "crack" or "hissing" after switching to the next volume position, the higher the volume, the louder the crack. Then it plays normally.
Q: is there a similar experience, I mean is it normal?

I would be very thankful for any hint or advice.

BrasilSamba

1) There is no way to charge with USB. You need a wall outlet (110V - 240V). The charger is for charging an extra battery (at home - before you go out etc.)

2) There is still problems with cue support (when it is turned on, the player will restart again and again) with latest firmware AFAIK.

3) The SD card must - has to be - a SDHC card. You can't use a SDXC card for upgrading firmware on HM-901, only music.

4) NOT normal. I haven't heard any cracking sound or hiss when turning the volume up or down. However, since it's a stepped attenuator there WILL be positions where you have selected between two levels and this will give you channel imbalance.

1) There is no way to charge with USB. You need a wall outlet (110V - 240V). The charger is for charging an extra battery (at home - before you go out etc.)

2) There is still problems with cue support (when it is turned on, the player will restart again and again) with latest firmware AFAIK.

3) The SD card must - has to be - a SDHC card. You can't use a SDXC card for upgrading firmware on HM-901, only music.

4) NOT normal. I haven't heard any cracking sound or hiss when turning the volume up or down. However, since it's a stepped attenuator there WILL be positions where you have selected between two levels and this will give you channel imbalance.

In regards to #4, try fully rotating the attenuator a bunch of times to break it in. This is fairly common with new steppers.

Thank you very much for your help. All is clear now. It seems that HM901 sounds perfect but the use is somewhat limited. I travel with my camper with solar panel and EFOY device in areas where there are simply no outlets. So I will have to use a converter from 12 to 110V or use a generator which is noisy. I am also sad I cannot use it as USB DAC.
I will try SDHC card to be sure I have the latest update.
I started to be very concerned about the volume, then I saw Brunk's advice so I will follow it.

Thank you very much for your help. All is clear now. It seems that HM901 sounds perfect but the use is somewhat limited. I travel with my camper with solar panel and EFOY device in areas where there are simply no outlets. So I will have to use a converter from 12 to 110V or use a generator which is noisy. I am also sad I cannot use it as USB DAC.
I will try SDHC card to be sure I have the latest update.
I started to be very concerned about the volume, then I saw Brunk's advice so I will follow it.

You're welcome :) A few more things. Just buy one of those car outlet adapters that gives you the AC you need. Second, the 901 is a soon-to-be USB DAC thanks to the docking station that will be released in 1-4 months. Let us know if you have any trouble updating. Be sure to put the .zip update file at the root directory of the SDHC card, with name unchanged.

Yes, all you should need to do is fully rotate the stepped attenuator about 20-50 times and you should be good. There will be clicks/crackles between steps, this is the nature of the attenuator. Second, the clicks you're hearing when changing tracks is normal, as the DACs are switching clocks and stuff.